WO2011162813A1

WO2011162813A1 - Bimetallic target

Info

Publication number: WO2011162813A1
Application number: PCT/US2011/001115
Authority: WO
Inventors: Eugene Y. Ivanov; Eduardo Del-Rio
Original assignee: Tosoh SMD Inc
Current assignee: Tosoh SMD Inc
Priority date: 2010-06-23
Filing date: 2011-06-23
Publication date: 2011-12-29
Anticipated expiration: 2012-12-23
Also published as: TW201207139A

Abstract

A bimetallic rotary target formed of a first metal and a second metal for use in a sputtering apparatus. The rotary target including a target tube having a plurality of grooves or apertures formed therein. An insert being positionable within each of the grooves or apertures. The inserts including a locking mechanism that protrude from the side surface of the insert, wherein the locking mechanism is configured to contact the surface defining the grooves or apertures to secure the inserts within the target tube. Subsequently HIPing, C1Ping, electron beam welding, ultrasonic welding, mechanical fixture fit, or sintering integrally attaches the inserts to the target tube.

Description

BIMETALLIC TARGET

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority under 35 U.S.C. 1 19(e) to U.S.

Provisional Patent Application No. 61/398,273, filed June 23, 2010.

FIELD OF THE INVENTION

[0002] The present invention relates to sputter targets, and more particularly, to bimetallic rotary targets used in sputter deposition.

BACKGROUND OF THE INVENTION

[0003] The use of sputter targets to deposit coatings such as metal coatings or ceramic coatings on large area substrates such as glass or elongated flexible substrates is well-known in the art.

[0004] Sputter coating is typically known as an electric discharge type process which is conducted in a vacuum chamber in the presence of at least one gas. Typically, a sputtering apparatus includes a vacuum chamber, a power source, an anode, and one or more cathode targets which include a material used to deposit a layer of metal onto a substrate. When an electrical potential is applied to the cathode target, the gases adjacent to the surface of the target forms a plasma which bombards the target causing particles of the material from the target to become displaced, ejected, or sputtered from the target. This material, which has become sputtered from the target, typically contacts a substrate, thereby becoming deposited on the substrate. Repeated instances of the particles of the target contacting and being deposited on the substrate build a coating, or layer, on the substrate. When a sputtering process is conducted in the presence of a gas that is reactive with the target material, the byproduct of the target material and the reactive gas forms on the substrate so as to form a coating different than the original target material. Different types of sputtering targets may be used in this coating process (e.g., planar targets, rotational cylindrical targets, etc.). Magnetron type sputtering is one such example of a sputtering which is commonly used in the art. [0005] Cylindrical magnetron sputtering, wherein the substrate is located within a cylindrical target, is particularly suited for coating three-dimensional complex objects, such as those used for cutting tools, biomedical de-ices, optical fibers, and so on.

Cylindrical magnetron sputtering devices are well known to those of ordinary skill in the art.

[0006] FIG. 1 illustrates an embodiment of a conventional magnetron sputtering apparatus. The apparatus includes metallic walls 1 of a vacuum chamber 2 in which a sputtering process is performed. A cylindrical rotary target 3 is supported by supports 5 located at each end of the rotary target 3 so that the target is rotatable about an axis 7. Gas is supplied into the sputtering chamber via a gas supply 8, and the chamber is evacuated to a pressure less than atmospheric via at least one vacuum pump 10. A substrate 9, such as a glass substrate for example, is moved beneath the target 3 via rollers or the like (not shown) as the rotary target 3 rotates. A plasma is generated within the vacuum chamber 2 by applying a voltage from a power supply 12 to the sputtering target 3 which has a negative charge relative to the walls 1 or the like which may be grounded. The plasma is positioned adjacent a sputtering zone of the target. The sputtering zone on the target can be controlled by way of at least one magnet 4 located within the rotary target 3 or at any other suitable location. As material from the rotary target 3 is released from therefrom, the disunited particles contact the upper surface of the substrate 9, wherein continuous operation of this process generates a layer, or coating, or material on the surface of the substrate 9.

[0007] While the sputtering apparatus shown in FIG. 1 produces a homogenous deposited layer of material, there exists a need for a rotary target that can produce a bimetal, or multi-metal layer on a substrate.

BRI EF SUMMARY OF THE INVENTION

[0008] In one aspect of the present invention, a bimetallic rotary target is provided. The bimetallic rotary target includes a cylindrical target tube formed of a first metal. The target tube has a first distal end, an opposing second distal end, an outer surface extending between the first and second distal ends, and a central axis extending normal to the first and second distal ends. The bimetallic rotary target also includes a plurality of apertures formed through the outer surface of the target tube. The bimetallic rotary target further includes a plurality of inserts formed of a second metal that is different than the first metal. One of the plurality of inserts is disposed within each of the plurality of said apertures, wherein each of the inserts includes a locking mechanism projecting therefrom. The locking mechanism contacts the aperture to secure the insert therewithin.

[0009] In another aspect of the present invention, a method for producing a bimetallic rotary target is provided. The method includes providing a cylindrical target tube formed of a first metal. The target tube has a first distal end, an opposing second distal end, an outer surface extending between said first and second distal ends, and a central axis extending normal to the first and second distal ends. The method further includes forming a plurality of apertures through the outer surface of the target tube. The method also including disposing an insert into each of the plurality of apertures. The inserts are formed of a second metal that is different than the first metal. Each of the inserts includes a locking mechanism projecting therefrom. The method also includes integrally attaching the inserts to the target tube.

[0010] Advantages of the present invention will become more apparent to those skilled in the art from the following description of the embodiments of the invention which have been shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0011] These and other features of the present invention, and their advantages, are illustrated specifically in embodiments of the invention now to be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:

[0012] FIG. 1 is a schematic diagram of a sputtering apparatus commonly known in the art;

[0013] FIG. 2 is a perspective view of an embodiment of a rotary target;

[0014] FIG. 3 is an end view of another embodiment of a rotary target;

[0015] FIG. 4 is a splayed view of the rotary target shown in FIG. 2;

[0016] FIG. 5 is a perspective view of another embodiment of a rotary target;

[0017] FIG. 6 is a splayed view of the rotary target shown in FIG. 5; [0018] FIG. 7 is a perspective view of yet another embodiment of a rotary target;

[0019] FIG. 8 is a splayed view of the rotary target shown in FIG. 7;

[0020] FIG. 9 is a perspective view of a further embodiment of a rotary target;

[0021] FIG. 10 is a splayed view of the rotary target shown in FIG. 9;

[0022] FIG. 1 1 is a splayed view of an embodiment of a target tube;

[0023] FIG. 12 is an embodiment of a cutting pattern of grooves of the target tube shown in FIG. 1 1 ;

[0024] FIG. 13 is a side view of an embodiment of an insert;

[0025] FIG. 14 is a cross-sectional view of a portion of a target tube having an aperture formed therein;

[0026] FIG. 1 5 is a side view of an embodiment of a cylindrical insert;

[0027] FIG. 16 is a side view of another embodiment of a cylindrical insert;

[0028] FIG. 17 is a side view of yet another embodiment of a cylindrical insert.

[0029] It should be noted that all the drawings are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of these figures have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference numbers are generally used to refer to corresponding or similar features in the different embodiments. Accordingly, the drawing(s) and description are to be regarded as illustrative in nature and not as restrictive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0030] Referring to FIGS. 2-4, an exemplary embodiment of a bimetallic rotary target 20 is shown. The rotary target 20 is an elongated, substantially cylindrical member having a substantially circular cross-sectional shape. The rotary target 20 includes a first distal end 22 and an opposing second distal end 24. In an embodiment, the first and second distal ends 22, 24 are substantially planar. In another embodiment, the first and second distal ends 22, 24 have a step-like configuration to be received by the end supports 5 (FIG. 1 ). It should be understood by one of ordinary skill in the art that the first and second distal ends 22, 24 can be configured in any manner sufficient to be received by the end supports 5 for rotation about a central axis 26.

[0031] In an embodiment, the rotary target 20 is formed as a cylindrical tube having concentric layers. In the embodiment illustrated in FIG. 3-4, the rotary target 20 includes a backing tube 28, a target tube 30, and at least one insert 32 operatively connected to the target tube 30. The backing tube 28 can be formed of any material sufficient to provide support to the target tube 30 while substantially un-reactive or inert during a sputtering process. In another embodiment, the rotary target 20 is formed without a backing tube 28, as shown in FIG. 2. The target tube 30 is formed of a first metal and the at least one insert 32 is formed of a second metal that is different from the first metal of the target tube 30. Any number of inserts 32 can be used to form the pattern of the second metal about the central axis 26. For example, FIGS. 2 and 4 illustrate a continuous spiral pattern about the central axis, and it should be understood by one of ordinary skill in art that any number of inserts 32 can be used to form the spiral pattern.

[0032] As shown in FIG. 3, the spiral pattern of inserts 32 form an angle Θ relative to the central axis 26. In the illustrated embodiment, the angle Θ is about 45°, but it should be understood by one of ordinary skill in the art that the angle Θ of the alignment of the inserts 32 relative to the central axis 26 may be greater than 0° and less than 180°. In an embodiment, a single insert 32 is operatively attached to the target tube 30 to form the spiral pattern. In another embodiment, a plurality of inserts 32 are positioned immediately adjacent to each other to form the spiral pattern on the target tube 30.

Other patterns of inserts 32 can be created and operatively attached to the target tube 30, as will be discussed below. In an embodiment, the width W of the inserts 32 is substantially the same. In another embodiment, the width W of the inserts 32 varies depending upon desired metal ratios in the rotary target 20. It should be understood by one of ordinary skill in the art that the inserts 32 can be formed having any width W sufficient to produce a desired sputtering deposition composition. The distance between adjacent rings of the insert 32 is substantially the same along the entire longitudinal length of the rotary target 20. By maintaining a consistent spacing of the secondary metal, the resulting deposited layer should be substantially consistent in both thickness as well as composition.

[0033] As shown in FIG. 3, the backing tube 28 and the target tube 30 are concentrically aligned. In an embodiment, the backing tube 28 and the target tube 30 are fixedly attached to each other. In another embodiment, the target tube 30 is releasably attached to the backing tube 28 such that, for example, when the target tube 30 is spent or no longer providing sufficient deposition quality, the target tube 30 can be easily removed from the backing tube 28. The radially inner surface of the backing tube 28 has a first radius R| , and the radially outward surface of the backing tube 28 has a second radius R₂. The radially inner surface of the target tube 30 has a first radius R₂, and the radially outward surface 38 (FIG. 14) of the target tube 30 has a second radius R₃. It should be understood by one of ordinary skill in the art that the radii Rj, R₂, R₃ as well as the length L of the rotary target 20 can be any dimensions sufficient for the rotary target 20 to be used in any conventional sputtering system.

[0034] The target tube 30 is formed of a homogeneous metal or a metal alloy. The target tube 30 is formed of the primary target material to be deposited on a substrate, whereas the inserts 32 are formed of a secondary target material or doping target material to be deposited with the primary target material. For example, the target tube 30 and inserts 32 may be formed of tungsten (W), tantalum (Ta), tellurium (Te), copper (Cu), molybdenum (Mo), indium (In), gallium (Ga), aluminum (Al), vanadium (V), niobium (Nb), chromium (Cr), or any other metal or an alloy of any combination of metals for use in sputter deposition, provided the target tube 30 and inserts 32 are formed of different materials to form a bimetallic rotary target 20.

[0035] In another exemplary embodiment of a rotary target 20, as shown in FIGS. 5-6, the inserts 32 are attached to the target tube 30 in a spiral-like orientation, wherein the spiral is non-continuous. The non-continuous spiral pattern is formed by integrally attaching a plurality of inserts 32 to the target tube 30, wherein each insert is spaced- apart from each other in both the longitudinal as well as the radial manner.

[0036] In yet another exemplary embodiment of a rotary target 20, as shown in FIGS. 7-8, the inserts 32 are located within a plurality of aligned apertures 36 (FIG. 14) forming a spiral-shaped pattern about the central axis 26. Each of the inserts 32 is formed as a plug that is insertable into the apertures 36 and subsequently integrally attached to the target tube 30. In an embodiment, the inserts 32 have a substantially circular cross-sectional shape. In another embodiment, the inserts 32 have a square, rectangular, or triangular cross-sectional shape, but the inserts 32 may have any cross- sectional shape, provided each of the inserts 32 has the same shape. The dimensions of each of the inserts 32 may be the same or vary between inserts 32. The inserts 32 are spaced both radially and longitudinally from each other, thereby forming the spiral pattern or other pre-determined pattern about the central axis 26.

[0037] In a further exemplary embodiment of a rotary target 20, as shown in FIGS. 9- 10, the inserts 32 are located within a plurality of aligned apertures forming a plurality of rings about the central axis 26. Each of the inserts 32 is formed and shaped similar to the inserts 32 described above with respect to the embodiment shown in FIGS. 7-8.

[0038] As explained above, the rotary target 20 is formed with or without a backing tube 28. The target tube 30 can be any cylindrical target for sputtering commonly known in the art formed in any conventional manner. With respect to the embodiments illustrated in FIGS. 2-6, a plurality of grooves 34 are cut into the outer surface of the target tube 30, and the inserts 32 are received within each groove 34, as shown in FIGS. 1 1 -13. The grooves 34 are formed tangentially to the target tube 30, and the depth that the groove extends 34 radially inward varies from one end of the groove 34 to the opposing end. The overall shape of the grooves 34 is in the form of a truncated circle. The size and shape of the inserts 32 correspond to the size and shape of the

corresponding groove 34. The width of the inserts 32 is substantially the same as the width of the corresponding groove 34. The grooves 34 can be cut in an orientation substantially perpendicular to the central axis 26 or at an angle relative thereto, as explained above. The grooves 34 are cut into the target tube 30 sequentially in an aligned manner such that a substantially spiral-shaped pattern is formed along the length L of the target tube 30 about the central axis 26. In another embodiment, the groove 34 formed into the target tube 30 in the embodiment illustrated in FIGS. 5-6 is a non- continuous groove 34, as shown in FIG. 1 1 . The grooves 34 can be cut into the target tube 34 by way of a saw, a laser, or any other conventional means of cutting a groove into a rotary target 20.

[0039] Regarding the embodiments shown in FIGS. 7- 10, apertures 36 are formed through the outer surface 38 of the target tube 30. In an embodiment, the apertures 36 are formed by drilling. In another embodiment, the apertures 36 are formed using a CNC machine. In yet another embodiment, the apertures 36 are formed using laser cutting. It should be understood by one of ordinary skill in the art that the apertures 36 can be formed in any conventional manner. The apertures 36 shown in the embodiment illustrated in FIG. 14 are cylindrical, having a substantially circular cross-sectional shape, but it should be understood by one of ordinary skill in the art that the shape of the apertures 36 can be formed as any shape. As shown in FIG. 14, an aperture 36 is formed into the target tube 30 through the outer surface 38 thereof. The aperture 36 has a width Si and a depth S₂. In an exemplary embodiment, the width Si is about 5.08 mm wide and the depth S₂ is about 7 mm deep extending from the outer surface 38. It should be understood by one of ordinary skill in the art that the width and depth of the apertures 36 may vary depending on the overall dimensions of the rotary target 20, and the apertures 36 can be any dimensions relative to the target tube 30 to produce a desired sputter deposition composition.

[0040] FIGS. 15- 17 illustrate exemplary embodiments of inserts 32 that are receivable in an aperture 36 formed into the target tube 30. Each of the illustrated embodiments of the insert 32 includes a locking mechanism 40 that operatively attaches the insert 32 to a corresponding aperture 36 when the insert 32 is received in the aperture 36. In the embodiment illustrated in FIG. 15, the insert 32 includes a first surface 42 that is substantially vertical and a second surface 44 extending from and formed at an angle relative to the first surface 42, thereby forming the locking mechanism 40. In the illustrated embodiment, the second surface 44 is oriented at an angle of about 45° relative to the first surface 42. In other embodiments, the second surface 44 can be formed at an angle of between about 1 ° and about 89° degrees relative to the first surface 42. In an embodiment, the locking mechanism 40 extends downwardly from the upper surface 48 of the insert 32 about 0.50 mm. It should be understood by one of ordinary skill in the art that the angle at which the second surface 44 is oriented with respect to the first surface 42 and the distance at which the second surface 44 extends at an angle from the upper surface 48 can be any angle or distance sufficient to allow the inserts 32 to still fit within a corresponding aperture 36 in the target tube 30 while substantially filling the void of the aperture 36

[0041] In the embodiment illustrated in FIG. 16, the insert 32 includes a first surface 42 that is substantially vertical and a second surface 44 extending from the first surface 42, thereby forming the locking mechanism 40. The second surface 44 is a rounded protrusion that forms a bump or protrusion that extends laterally from the vertically oriented first surface 42. The protrusion formed by the second surface 44 is spaced apart from the upper surface 46 of the insert 32.

[0042] In the embodiment illustrated in FIG. 17, the insert 32 includes a first surface 42 that is substantially vertical and a second surface 44 extending from the first surface 42, thereby forming the locking mechanism 40. The second surface 44 is a rounded protrusion that forms a bump or protrusion that extends laterally from the vertically oriented first surface 42. The protrusion formed by the second surface 44 is immediately adjacent to the upper surface 46.

[0043] In an embodiment, the width Lj of the insert 32 between the opposing first surfaces 42 is slightly smaller than the width Si of the aperture 36 into which the insert 32 is being received. The width L₂ of the locking mechanism 40 is sized such that it is substantially the same size as the width Si of the aperture 36 into which the insert 32 is being received. The height L₃ of the insert 32 extending from the upper surface 48 is substantially the same as the depth S₂ of the aperture 36. The locking mechanism 40 is configured to secure the insert 32 within the aperture 36 when disposed therewithin by way of a friction fit or press fit. However, it should be understood by one of ordinary skill in the art that the dimensions of the insert 32 and the locking mechanism 40 can be slightly larger or slightly smaller than the aperture 36 into which it is disposed. While the locking mechanism 40 is described above with respect to the inserts 36 formed as plugs insertable into apertures 36, the same locking mechanism 40 design can also be utilized for the inserts 32 positionable within grooves 34.

[0044] Assembly of the rotary target 20 involves forming the grooves 34 or apertures 36 into the target tube 30. The inserts 32 are then positioned within corresponding grooves 34 or apertures 36 of the target tube 30. The inserts 32 should form a snug or friction fit within the corresponding groove 34 or aperture 36 by way of contact between the locking mechanism 40 and the surfaces defining the groove 34 or the aperture 36. In an embodiment, the target tube 30 and inserts 32 are then subjected to hot isostatic pressing (HIPing), cold isostatic pressing (CIPing), electron beam welding, ultrasonic welding, sintering, friction fitting, or any other manufacturing method of integrally attaching the inserts 32 to the target tube 30. The resulting rotary target 20 is then machined to finish the outer surface thereof. EXAMPLE 1

[0045] A titanium (TI) target tube 30 having a length of 550 mm with an outside diameter D₃ of 1 54 mm with a plurality of grooves 34 formed therein with a width W of 1 .5 mm and a maximum depth of 7 mm. The grooves 34 are oriented relative to the central axis 26 at 45° thereto. A plurality of inserts 32 having a locking mechanism 40 are configured to fit within each of the grooves 34.

EXAMPLE 2

[0046] A tungsten (W) target tube 30 having a length of 550 mm with an outside diameter D₃ of 154 mm includes a plurality of apertures 36 formed therein in a spiral pattern about the central axis 26, as shown in FIG. 9- 10. The spiral pattern of apertures 36 is oriented relative to the central axis 26 at about 45° relative thereto. A plurality of cylindrical inserts 32 are formed of Aluminum (Al) having a width Li slightly smaller than the width Si of the aperture, but the locking mechanism 40 has a width L₂ of 5.08 mm, the same width as the width Siof the aperture 36. The insert 32 has a length L₃ of 7mm. The inserts 32 are press-fit into the apertures 36. The combined target tube 30 and inserts 32 is then processed in a HIPing procedure to integrally attach the inserts 32 to the target tube 30. The rotary target 20 is then machined to remove any flashing or excess material.

[0047] While preferred embodiments of the present invention have been described, it should be understood that the present invention is not so limited and modifications may be made without departing from the present invention. The scope of the present invention is defined by the appended claims, and all devices, process, and methods that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.

[0048] What is claimed is:

Claims

1 . A bimetallic rotary target comprising:

a cylindrical target tube formed of a first metal, said target tube having a first distal end, an opposing second distal end, an outer surface extending between said first and second distal ends, and a central axis extending normal to said first and second distal ends;

a plurality of apertures formed through said outer surface of said target tube; a plurality of inserts formed of a second metal that is different than said first metal, one of said plurality of inserts disposed within each of said plurality of said apertures, wherein each of said inserts includes a_. locking mechanism projecting therefrom, said locking mechanism contacting said aperture to secure said insert therewithin.

2. The bimetallic rotary target of Claim 1 , wherein said first metal and said second metal are formed of tungsten (W), tantalum (Ta), tellurium (Te), copper (Cu), molybdenum (Mo), indium (In), gallium (Ga), aluminum (Al), vanadium (V), niobium (Nb), chromium (Cr), or an alloy of metals.

3. The bimetallic rotary target of Claim 2, wherein said first metal is tungsten (W) and said second metal is aluminum (Al).

4. The bimetallic rotary target of Claim 1 , wherein said apertures are formed as a spiral pattern about said central axis.

5. The bimetallic rotary target of Claim 1 , wherein said locking mechanism includes an upper surface extending normal to a first surface, a second surface extending from said first surface to form said locking mechanism.

6. The bimetallic rotary target of Claim 5, wherein said second surface extends from said first surface at an angle relative thereto, said second surface extending between said first surface and said upper surface.

7. The bimetallic rotary target of Claim 5, wherein said second surface extends from said first surface to form a rounded protrusion.

8. The bimetallic rotary target of Claim 7, wherein said rounded protrusion is spaced apart from said upper surface of said insert.

9. The bimetallic rotary target of Claim 7, wherein said rounded protrusion is positioned immediately adjacent to said upper surface of said insert, said second surface extending between said first surface and said upper surface.

10. A method for producing a bimetallic rotary target comprising:

providing a cylindrical target tube formed of a first metal, said target tube having a first distal end, an opposing second distal end, an outer surface extending between said first and second distal ends, and a central axis extending normal to said first and second distal ends;

forming a plurality of apertures through said outer surface of said target tube; disposing an insert into each of said plurality of apertures, said inserts formed of a second metal that is different than said first metal, wherein each of said inserts includes a locking mechanism projecting therefrom;

integrally attaching said inserts to said target tube.

1 1 . The method of Claim 10, wherein integrally attaching includes HIPing, CIPing, electron beam welding, ultrasonic welding, or sintering.

12. The method of Claim 10, wherein said first metal and said second metal are formed of tungsten (W), tantalum (Ta), tellurium (Te), copper (Cu), molybdenum (Mo), indium (In), gallium (Ga), aluminum (Al), vanadium (V), niobium (Nb), chromium (Cr), or an alloy of metals.

13. The method of Claim 12, wherein said first metal is tungsten (W) and said second metal is aluminum (Al).

14. The method of Claim 10, wherein said apertures have a substantially circular cross-sectional shape.